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We were right to expect a lot of kids at the Faire, so we modified our injection machine with a larger base for allowing more leverage with an extension on the plunger lever. Our hope was that any kid who can do a pullup could make their own drumsticks. In practice it still took 2 or 3 kids hanging on the bar to really do it – it made for some good photos and nervous parents tho.
bonus: The base and plunger lever extension are removable so now it can all fit in my car
@lila we run ours at 263 barrel and 265 nozzle temp, preheat the mold w/ heat gun or LP torch and it still requires a lot of pressure. Even then, I dont like to press out anything more than 6 cu.in. in volume. I’m taking some time this week to mod ours so that it’s a little easier to operate at public demonstrations. would love to know if you made progress with your design mods
we shredded lots of leaves for worm bedding with good success. We removed the sieve and were very careful that no stones made it in there
Cardboard was decent…. its not exactly self-feeding, so it’s bit laborious
following this one closely…. thanks for sharing
I’ve put a little thought in to this, but with little tangible progress so far. Hoping to get to it this in the coming months….
the idea is to use something like a simple indirect flame oven like the ‘butterfly camping oven’ for coarse tuned heating with a variable speed fan that meters in fresh air for fine tuned heating.
I’m assuming it’s going to need a lot of mass (firebrick, cob, etc) to ease the wild temperature swings – it would take much longer to get to temperature, so I expect it’s something to run when in production mode only
would love to hear if anyone else has had similar thoughts
Hi @fperez394 ! So far, we’ve stuck mostly to the limb spreaders, along with some fruit bowls from the extrusion machine. This stuff extrudes nice and smooth, better than anything else I’ve sent trough it. It’s so easy on the equipment.
I’ve read it’s almost always virgin (non recycled) Linear LDPE for added burst strength. I don’t know about your farm, but here in western NC conventional farmers rarely use it for more than one season.
It’s a real tragedy for the environment, and kind of a gold-mine for us.
Ag film mulches are the new priority – too dirty for conventional recyclers. I’ve learned recently there is only one facility in the entire USA that accepts it.
this thread has some of the better compression specs that I’ve come across on here. He was working in bars – converted to psi there was still a huge range of what’s considered ‘enough pressure’. We landed somewhere around 5 psi spec, but then when we got to building our little press, I just grabbed a few automotive bottle jacks. You can get a 20 ton bottle jack (massive pressure) for less than $50.
I’m looking to move towards pressing blocks from dirty agricultural LDPE “mulch” films… will be following your progress for sure, and will post when we’ve got something to share! good luck!
Glad to see you guys are looking into this.
This article has some interesting figures about adding pyrolysis products into building materials. The author focuses much on wood charcoal, but I suspect solids from the plastic pyroysis (aka carbon black) could have a role in improving concrete and plastic composites. Energy in the form of heat or liquid fuel could be extracted from the plastics prior to tying up the remaining carbon in building materials.
We run our heavy pyloysis oils through a babington style burner we modded from a conventional oil heater. We’ve also used these oils as an asphalt binder (tarmac) – our sample isn’t much to show for, but it’s held up for over 3 years outside now. I suspect raw plastic oils could be used in a similar process. Though I doubt we’ll be able to find a contractor that would let us use their equipment and scale up…
I hear alot about people saying they COULD make diesel/gasoline from plastic pyrolysis oils, but I don’t see much of it actually being done on small scale.
I’ve been watching this closely too. PP user plaspod turned me on to the ‘Wastebot’ designed by Ben from Victory Gasworks.
he offers diy plans for $100 – to fund his further work with waste to fuels..
it’s a multimachine of sorts, using charcoal as both a heat source and a catalyst for breaking down long chains of plastic pyrolysis gases into their gaseous elemental form, that can later be burned for domestic heating or other light industrial processes. Gases can otherwise be routed through condensing units for collection before reburn via the charcoal catalyst.
true regulations are likely a nightmare with this – but this represents a kind of tech that seems feasible only when small
Our crew just wrapped up building what he calls the diy model – to date we’ve had 3 runs on it, mostly successful. This thing is great for dealing with hard to remove sticky paper labels, waste bits from PP processes that can’t be re-shredded, or some of the food waste covered plastics that are too gross to bother washing. For our last run we used 9 lbs of charcoal to gasify 5 lbs of these dirty plastics (no pvc, #7’s) in about 1.5 hrs. These aren’t impressive numbers… but we’re getting there.
with some dedication to our local scrapyard I’ve got less than $800 US at this point
Your approach is very similar to mine, we have a small fabrication/machine shop located at our agricultural charcoal facility in Western North Carolina. A big part of our work is around using ag plastics as feedstocks, and finding alternate uses for the machines during relevant seasons. for ex, the shredder doubles as a food waste and leaf litter grinder, for our vermiculture process, or for the 2 weeks out of the year that you need an apple crusher; we’ve used our extrusion machine for pelleted fish feed. Our plastics feedstocks are now nearly entirely hdpe milk jugs from a nearby dairy, and black ldpe irrigation drip tapes. We’ve tried extrusion of chicken netting fenceposts, though the process so far consumes far too much time and energy.
One useful ag waste to ag product has been our fruit tree limb spreaders.
Would love to keep in touch and see how your approach works in Italy
very nice! Love the pin idea
Coming back to this – i should say that our little shredder has worked very well for almost all #4 LDPE we’ve fed it. Agricultural drip tape is almost self feeding. which is nice. I made a few mistakes early on: I doubled the amount of cutting area, rely to heavy on the shear pin, and spin it at 60 RPM. In hindsight I’d go much slower and drive it with a belt or something…
For fun: attached is a photo of the tumbler attachment our crew fabbed up shortly after I originally posted last year.
ha, good to come back to this over a year later
we ultimately set ours up as a multi-machine – i think i’ve read others doing it here too… spider coupling (with high torque urethane insert) joins the gear box to the shredder shaft – which we made extra long too. We can remove the shredder from the frame and drop in a tumbler unit (made from a 15 gal lp tank) for making greensand. Or pop a roller mill in place.
I may have messed up by drilling a thru-hole through the shredder shaft and dropping in a shear pin. Would still love to know what others are doing for over-torque safety.
With my 3HP I shredded lots of leaves last fall, used it for some animal feed prep, shredded some woody herbs for soapmaking, etc. But I really had to baby it. Kept popping shear pins. Of course apples fall through it like water… but I didn’t use stainless steel… so there ya go.
I’ve been approached by a few locals for shredding jobs – a papermaker wants kudzu vines shredded… a guncase maker wants excess foam shredded for ‘bean’ bag chairs… sadly neither of these worked well in the 60 RPM unit.
On another note – We got a hold of a Weima Wl-4 !!! (1992 model) It’s been outside for years in rain and snow… needless to say the electronics are toast. Modified it last week to run off our tractor PTO and hydraulics… can’t wait to show it off in a few days! I gotta say I’m with @anne-barbier on this one though – I’d def recommend anyone serious about shredding for more than a hobby go out and track down a salvage industrial unit.
@plaspod – thanks for sharing details
We operate a series of Adam style retorts for biochar (ag. charcoal) production in north carolina, USA. We capture and store excess heat in 18K gallon water storage. Our process is started a simple downdraft wood chip gasifier, and becomes self sustaining after just an hour or so. Seems we’re doing something similar, though maybe on just a slightly larger scale. Would love to talk to you more about your work.
I’ll admit our heat exchange has been a bit dissapointing – only about 2M Btus stored / 1200 lbs of sawmill waste. Our big project now is using gas/process heat as it’s made – prior to storage – for drying tasks and large plastic compression moulding work.
Care to talk privately? We’re leading a workshop for our community on our work (so far) with plastics recycling – I’d be honored if you or someone else in your group wanted to share your work in plastic pyrolysis via skype with our group.
Nice Work, Bravo! I love the scale.
Am I right – You’re mixing plastic and torrefied wood in a downdraft gasifier?
Care to share how you currently process beach plastic to fuel pellets?
I too would be curious on plastic/wood ratios.
In the US we don’t call it a boiler if it’s open to atmospheric pressure… Legally, things change a lot when it’s called a boiler.
How small is small scale? If we pursue this, I’ll keep it on a pallet. There’s too many unknowns to scale up from there. Toxicity of condensates is a huge concern for me. That, and gasses that don’t get completely combusted.
Thanks for the tip! I’ve never heard of this plasma technique. Seems the way to deal with the most hazardous of wastes
I’m going to bench this project for a least a bit. We’re switching gears for the short term: as we use them now, our charcoal retorts have lots of leftover heat we can readily use for large compression molding projects. Still though, we’re collecting plenty of odd nuggets of plastic from our extrusion and injection experiments that would be the perfect feedstock. One step at a time…
@frogfall – Artisan scale.. yes! I’m not at all interested in large scale incineration plants that require massive amounts of waste plastic to stay viable. I think we can all agree reducing plastic is the first necessary step.
Our ‘wood oil’ (sometimes called bio-crude) represents about 20% of the total liquids yield from our biochar process. The other 80% is this acidic, water soluble stuff commonly called wood vinegar, or pyroligneous acid, of which methanol is only a small part. We don’t capture syngas, but it is burned to sustain the process, excess is burned with the energy captured in large hot water storage tanks. We’ve played around with syngas in ICEngines, but it’s dirty, and very corrosive.The bio-crude oil is shelf stable when stored in air tight containers. We’re burning crude made 4 years ago in a modified babington style gun burner. This stuff is energy dense and can burn very hot… hot enough for cast iron.
Definitely want to keep separate processes. And keep a plastic py unit small and experimental. Extra oil would be fantastic. The plastic char can be used as ‘carbon negative’ material in concrete and plastic composites. Or gasified for ICengines… we’ve had success with gasified charcoal in a lawnmower engine. If you’re curious, I write about our work at livingwebfarms.org/blog
I’d love to get a PP oven fired off of plastic py-oils. The electricity needs of running this equipment has always bugged me.
Global collaboration would be amazing. I’m confident we can do a small batch system. Anything automated/continuous would be a worthy challenge.
Thanks, Sonik. Great link. You too Frogfall. JL, I’d love to be a part of a collab if you want to go for something more precious-plastics-scale…. We’re near Asheville NC.
Our biochar systems are batch pyrolysis units – we’ll heat woody biomass up to 950F over the course of 8 or so hours. Our condensation process yields between 5 and 10 gallons of ‘wood oil’ / day. I wouldn’t have a clue what to expect from these downcycled plastics as feedstocks. Anyone who’s done these home scale projects know target temps?
Need to get those chemistry chops up – who knows how to figure what’s in these plastic pyrolysis gas condensates? And is there a ‘generally regarded as safe’ place to start?
This seems like a great way to deal with the stuff that’s downcycled beyond it’s utility. Reduce – Reuse – (Repair, Remanufacture) Recycle – RETORT!
I don’t know if this helps much for UV, but I’ve read a bit on using fine charcoal powders in plastics for added strength and fire resistance. It doesn’t bond molecular like you say, but it might be a tighter bond than you think.
I came across this last night, with electron microscope images, from your neighbors in NZ: https://link.springer.com/article/10.1007%2Fs00267-018-1033-6
Also, near us in the southeast USA, Albert Bates writes a lot about embedding charcoal/plastic composites.
I hope to get into this soon, and would love to hear if you’ve made any progress here. I’ve been keeping separate UV treated plastics from my others – agricultural drip tape has been good to us.
@benc have you made any progress with this? Check out Babington style burners for atomizing heavy, raw liquid fuels. this is where my head has been for a while now. Would love to share our progress if anyone’s interested. It’s too raw and intense of heat for forming plastics, but possibly after water heat exchange, could be used to shroud the oven w/ heat.
Agreed 99%. Not convinced we should ‘dump’ as much plastic as possible in to one object… it is ‘precious’ right? The world has enough fidget spinners and pencil holders.
We’re aiming for products that are very specific to an area where we’re most familiar: homesteading, small farms, organic ag. A shop of our size may be able to make an impact if we aim to make one product very well. Innovation is hard.
@benc I have lots of experience with pyrolysis of biomass, and reclamation of liquid coproducts, all on a fairly small scale. We convert roughly 4 tons of biomass to charcoal a week in our retorts. The process heat and oil from this process is how we fuel many processes around our farm.
I would love to experiment with this kind of work with plastics and tires. I wouldn’t run it through our machines as is, but we’d be interested in constructing a bench top model for this.
MIG or flux core welding (wire welding) is definitely good enough for shredder. And by far the easiest to learn on. Sure, you can get a low cost stick welder that will do almost anything, but most people find this a little frustrating to learn on. The old timers think everyone should learn on stick first – I guess they have their reasons…. I started with a very low cost 120v flux core welder (works almost the same as MIG) and had to upgrade fairly quick… but I was still able to do a lot of art projects with that little thing. Both mig and flux core welding are referred to as ‘Wire Welding’. Pay close attention to preparing the the steel and any one of these processes will do. When getting started, lots of people around here will take an evening course at a community college and gain access to welding equipment for the duration of the class. I think it’s a popular mechanics book that I read early on… but there’s a good manual for getting started that you can buy at an auto parts store.
A friend of mine that does the fabrication for New England Biochar (cape cod, ma) cut the blades for me. They’re the standard size as in the files, but modified to 1″ square holes. If you’re interested I can reach out to him.
Yes my shredder is working… admittedly not as well as I expected. I made a few mistakes I would change next time, but having the blades plasma cut for $100 is not one of them. We collect used milk jugs from a local dairy that has delivery and return service. They’re not big enough to afford the glass washing equipment, so they’re stuck using HDPE jugs. So, for now, we get free plastic and they get to look good b/c the plastic stays local.
Also, It might be helpful to know what kind of overload protection people are using.
@wess – Is there a method you use to determine shaft size? I’m all the way down to 3/4″. I suspect this is going to be too small in the long run.
I’m about to ditch my sheer pin all together… and I’d like to know what my next weak link is! I’m guessing it’s the spider coupling insert.
I would love to know more about the coupling you guys are using.
I’ve got a 3HP Single phase motor, with a reduction to 60 RPM. I connected my gearbox to the shredder with a heavy spider coupling. I didn’t get my shredder shaft keyed – so I put in a sheer pin on the shredder side.
I haven’t figured torque yet, but we’re snapping sheer pins all the time.
My shredder has a 12″ opening – so quite a bit more teeth to bite. However, my experience shows it’s when the milk cartons, PET bottles, etc, fold over on themselves – even it’s only over couple of teeth – that it’s hardest on the shredder.